Hi Chris
I did visit your links, and I saw the applicability. Looks like they
decap with an acid spray, perhaps to try to leave the chip serviceable
- it's cheaper to dissolve everything away, if you only want the bare
die.
With the rosin method, I gather the epoxy is converted to sludge,
and then acetone is used to remove the sludge. (Rosin contains some
useful acids, effective against organics. It's not just about the
strength of the acid. Heat is going to help in any case to increase
the reaction rate, perhaps enormously.)
The fuming nitric sounds best, but it's a specialised operation.
With few Tubes available, and most of them useful, we should aim to
destroy as few as we can.
Cheers
Ed